change block title from motion to summary

Changes the title of the section ‘Motion’ to ‘Summary’ on the divisions#show. Seems a bit more intuitive because the motion is not what is there, but rather it contains a summary of what happened that should include the motion.

This probably relates to #584 .

![screen shot 2014-09-29 at 3 15 01 pm](https://cloud.githubusercontent.com/assets/1239550/4437457/f8703a6a-4797-11e4-8abd-e994855a8a68.png)